common/board_r.c: drop legacy and unused bi_enetaddr

The bi_enetaddr field in struct bd_info is write-only; nothing ever
reads back the value.

Moreover, the value we write is more or less random, and certainly not
something one can rely on: If the board has a writable environment and
the mac address has been stored there, we fetch that value. But if the
board doesn't, this code runs before initr_net() -> eth_initialize(),
and thus before the code in eth-uclass which fetches MAC addresses
from eeprom, fuses or whatnot and populates the (run-time) environment
with those values.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Tom Rini <trini@konsulko.com>

include/asm-generic/u-boot.h

@@ -48,7 +48,6 @@ struct bd_info {
 #endif
 	unsigned long	bi_bootflags;	/* boot / reboot flag (Unused) */
 	unsigned long	bi_ip_addr;	/* IP Address */
-	unsigned char	bi_enetaddr[6];	/* OLD: see README.enetaddr */
 	unsigned short	bi_ethspeed;	/* Ethernet speed in Mbps */
 	unsigned long	bi_intfreq;	/* Internal Freq, in MHz */
 	unsigned long	bi_busfreq;	/* Bus Freq, in MHz */